Obtain Keys Easier
There is an easy way to obtain the hard to get keys. You'll have to go to the cheat menu and select Resurrect in Place. Then select any track and locate a key in the air. Get directly underneath the key and press C-up many times (which will elevate you higher everytime you press C-up). You know have the key you couldnt reach.

Drive on Invisible Track
While driving on the stunt track, hit any of the ramps, preferably the purple half-pipe at a high rate of speed. Your car must be heading towards a wall. If you get enough height, you will easily clear the wall and fly into a black oblivion. You will be able to see the normal track if you look to the upper part of the screen. It is an awesome glitch that the devolpers should've picked up on.

Completed Circuit Code
I have a code for Rush 2: Extreme Racing USA that will bring you to the last race in the circuit. You do not even have to race! All you have to do is sit there until the time runs out. The code is,

Q K K X 6 2 B 5 D P ?
G 1 8 L K G @ X W W L

I got this code by myself. I raced the whole circuit to get the code!

Cheat menu
Hold (C-Up) + (C-Down) + (C-Left) + (C-Right) + (L) + (R) + (Z) at the settings screen to unlock a cheat option under "Audio". Then, highlight one of the following options on the cheat menu and enter the corresponding code. Note: Another way to activate the cheat options is to hold (L) + (R) + (Z) and rapidly tap (C-Up) + (C-Down) + (C-Left) + (C-Right). Alternately, enter the cheat menu code and highlight any cheat you wish to activate. Then, hold (L) + (R) + (C-Up) + (C-Down) + (C-Right) + (C-Left) + (Z) + (A), release the buttons, the repeat until the code activates.

Massive Mass
Hold (L) + (R) and press (C-Up), (C-Down), (C-Left), (C-Right).

Stunts
Hold (C-Down) + (C-Left) + (C-Up) + (C-Right) and press (A), (R), (Z), (L), (A), (R), (Z), (L), (R), (A), (Z), (L).

Killer Rats
Hold (L) + (R) and press (Z)x4.

New York Cabs
Press (R), (L), (Z), (C-Up), (C-Down), (C-Up)

Resurrect In Place
Hold (Z) + (C-Left) and press (C-Right). Then, hold (Z) + (C-Right) and press (C-Left).

Frame Scale
Hold (Z) + (C-Down) and press (C-Up). Then, hold (Z) + (C-Up) and press (C-Down).

Tire Scaling
Hold (Z) + (C-Left) and press (C-Right). Then, hold (Z) + (C-Right) and press (C-Left).

Auto-Abort
Quickly press (C-Up)x4.

Game Timer
Hold (Z) + (C-Down) and press (C-Up). Then, hold (Z) + (C-Up) and press (C-Down).

Fog Color
Hold (Z) and press (C-Left), (C-Up), (C-Right), (C-Down) three times.

Levitation
Hold (L) + (R) + (Z) and press (C-Up)x4.

Suicide Mode
Hold (Z) and press (C-Down), (C-Left), (C-Up), (C-Right) two times.

Super Tires
Hold (L) + (R) and press (C-Up), (C-Right), (C-Down), (C-Left) two times.

Invisible Tracks
Hold (L) + (R) and press (C-Down), (C-Up) five times.

Invisible Car
Hold (L) + (R) and press (C-Up), (C-Down) five times.

Super Speed
Hold (L) + (R) and press (C-Up), (C-Down), (C-Left), (C-Right).

Track Orientation
Hold (L) + (R) and press (C-Up), (C-Right), (C-Down), (C-Left) four times

Gravity
Hold (L) + (R) + (Z) and press (C-Left), (C-Up), (C-Right), (C-Down) three times.

Car Collisions
Hold (L) + (R) and press (C-Left), (C-Up), (C-Right), (C-Down) three times.

Cone Mines
Hold (Z) and press (L) + (R) four times.

Car Mines
Press (Z) + (C-Up), then press (C-Right), (C-Down), (C-Left)) six times.

Inside-out Car
Hold (C-Right) + (C-Down) and press (L), (R), (Z).

Damage
Press (R), (C-Down), (L) two times.

Invincibility
Press (L), (C-Up), (R) two times.

Invisible Car
Hold (L) + (R), and press (C-Up), (C-Down) five times.

Brakes
Hold (C-Up) + (C-Right) and press (Z)x3.

Super Tires
Hold (L) + (R), and press (C-Up), (C-Right), (C-Down), (C-Left)) two times.

Suicide Mode:
Hold (Z) and press (C-Down), (C-Left), (C-Up), (C-Right) two times.

Do the Dew!
Press (L) + (R) + (C-Down), (L) + (R) + (C-Left), (L) + (R) + (C-Up), (L) + (R) + (C-Right) two times, (Z).